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        <h1 class="fnt-sixcaps">Haba <span>Stress</span> Engineering</h1>
        <p class="description">Specializing in Heat Treatment &amp; Engineering Inspection</p>        
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         <h2 id="about-pwht-1">What is Heat Treatment?</h2>
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         <p>One of the purposes of heat - treating is to relieve stresses 
         caused when two pieces of metal are joint together by welding. 
         As the metal in welded area raised to fusion temperature, the 
         surrounding metal tends to expand but is restrained by the unheated 
         areas adjacent to the welded joint. As a result, the heated portion 
         is place under a compression stress, the magnitude of which may approach 
         and sometimes exceed the yield point of metal.</p>
         
         <p>Upon the cooling, the heated areas contract and set up reverse stresses, 
         with the result that when cooled to room temperature the metal in the weld area
         is under constant Tensile Stress. To avoid internal stresses, stress-relieving
         equipment is equally applicable for normalizing, annealing and pre-heating, and 
         electrical heating apparatus is proving successful in carrying out stress relieving
         requirements, for temperature up to 1100&deg;C.</p>
         
         <p>Control of temperature is an important feature and temperature in range of 60&deg;C to
          950&deg;C required to heat-treat the materials can be arrived at a specified rate of temperature
           increase. The heat can then be adjusted to maintain the area being stress relieved at the 
           temperature and period specified.Reducing the temperature at any given rate controls the cooling 
           period.</p>
           
           <h3>Question &amp; Answer</h3>
           
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                 Question: Why is post-weld heat treatment (stress relieving) sometimes necessary for welded vessels?             
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    Answer:
    During the welding process, the two metal pieces being joined are subject to extreme temperatures and
    can cause the crystalline structure of the metal to pass through various metallurgical phases. As a result, 
    hardening (and embitterment) of the metal can occur to varying degrees (usually dependent on carbon content).
    Heat treatment is designed to reduce the hardness in the heat affected zone of the metals and also increase 
    ductility in these sections.Various pressure vessel codes contain the specifics regarding the procedures for
    post-weld heat treatment.Heat is usually held for one hour per inch of thickness of the metal. The temperature used 
    is based on the "P-number" of the metals. P-numbers are assigned based on the chemical composition of the metals.
    Holding temperatures can range from 1100-1350 &deg;F (593-732 &deg;C).Our personnel will supervise any stress relieving 
    operations that the clients desires, making provision for yield at high temperatures and secondary stressing when cooling
    at the degree and duration of soaking temperature necessary for the material.</p>
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          <h4>Contact Us</h4>
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            <li><strong>Haba Stress Engineering</strong></li>
            <li>No. 59, Jalan Bukit 9, Kaw. MIEL, Bandar Seri Alam,</li> 
            <li>81750 Masai, Johore, Malaysia</li>
            <li>Email: info@heatstress.com.my</li>
            <li>Tel: (+6) 07-217&nbsp;3013</li>
            <li>Mobile: (+6) 013-721&nbsp;3013</li>
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